@article{Kentarou25102007,
author = {Kentarou, Kawaguchi and Fujimori, Ryuji and Aimi, Sayaka and Takano, Shuro and Okabayashi, Emi Y. and Gupta, Harshal and BrÜnken, Sandra and Gottlieb, Carl A. and McCarthy, Michael C. and Thaddeus, Patrick}, 
title = {Observation of C$_8$H$^-$ toward IRC +10216},
volume = {59}, 
number = {5}, 
pages = {L47-L50}, 
year = {2007}, 
doi = {10.1093/pasj/59.5.L47}, 
abstract ={Five rotational lines of the C$_8$H$^-$ ion were observed in the circumstellar envelope of IRC $+$10216 with the Nobeyama 45 m telescope. An improved value of the column density of the C$_8$H radical yielded a [C$_8$H$^-$]$/$[C$_8$H] ratio of 37%—nearly 4 times larger than the [C$_6$H$^-$]$/$[C$_6$H] ratio (8.6%) and nearly 1500 times the [C$_4$H$^-$]$/$[C$_4$H] ratio (0.024%), which may indicate more efficient formation of longer carbon chain anions. The excitation temperature of C$_8$H$^-$ (16$\;\pm\;$2 K) derived here is somewhat lower than that of the two smaller anions C$_6$H$^-$ (32 K) and C$_4$H$^-$ (23 K) in IRC $+$10216.}, 
URL = {http://pasj.oxfordjournals.org/content/59/5/L47.abstract}, 
eprint = {http://pasj.oxfordjournals.org/content/59/5/L47.full.pdf+html}, 
journal = {Publications of the Astronomical Society of Japan} 
}